High-resolution micro-LED display device and manufacturing method of the same

ABSTRACT

A manufacturing method of a micro-LED display device comprises forming a plurality of thin-film transistor array areas that includes a plurality of thin-film transistor arrays on a first substrate; forming a plurality of micro-LED array areas that includes a plurality of micro-LED arrays on a second substrate; transferring the plurality of micro-LED array areas that correspond to the plurality of thin-film transistor array areas onto the first substrate; forming a bank film on a third substrate over the first substrate; patterning the bank film to form a first bank layer that corresponds to a boundary area between the plurality of micro-LED arrays and a second bank layer that corresponds to an edge area of the plurality of micro-LED array areas, to form a pixel area and a pixel array area, and to remove the bank film in a boundary area between the second bank layers adjacent to each other; cutting the third substrate and the first substrate along a scribe zone that is set in a boundary area between the second bank layers adjacent to each other; and separating a plurality of pixel arrays that includes the plurality of thin-film transistor arrays and the plurality of micro-LED arrays from the first substrate and transferring the plurality of pixel arrays onto a fourth substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2018-0163161 filed on Dec. 17, 2018 in the Republicof Korea, which is hereby incorporated by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to a display device, and moreparticularly, to a high-resolution micro-LED display device and amanufacturing method of the same. Although the present disclosure issuitable for a wide scope of applications, it is particularly suitablefor reducing a boundary area between micro LEDs and minimizing crackpropagation to micro LED elements, which can be caused during amanufacturing process.

Description of the Background

In the information society where there is a growing demand for a varietyof home appliances, mobile electronic devices and the like, variousflat-panel display devices that are thin and lightweight are very muchin demand.

The flat-panel display device includes a liquid crystal display (LCD), aplasma display panel (PDP) display, an organic light-emitting diode(OLED) display, a micro light-emitting diode (micro LED) display and thelike.

Among such devices, the organic light-emitting diode and microlight-emitting diode use a self-light emitting element. They do notrequire an additional light source such as a backlight that is used fora liquid crystal display device. Thus, the organic light-emitting diodeand micro LED diode become thinner and can be used as various types ofdisplay devices.

In the case of an organic light-emitting diode that uses an organicmaterial, defect pixels are very likely caused by moisture and air.Accordingly, a structure that is capable of minimizing infiltration ofmoisture and air is required.

In the case of a micro LED display device that uses a micro LED elementthat includes an inorganic material such as GaN is not largely affectedby external environmental factors such as moisture, air, heat and thelike, thereby ensuring reliability.

The micro LED elements of micro LED display devices may display an imagewith luminance higher than that of the organic light-emitting diode andmay consume less energy than the organic light-emitting diode. This isbecause the micro light-emitting diodes have a high efficiency ininternal quantum. Accordingly, research into micro LED display deviceshas been actively performed in recent years.

SUMMARY

Accordingly, the present disclosure is directed to a high-resolutionmicro-LED display device and a manufacturing method of the same thatsubstantially obviate one or more of the problems due to limitations anddisadvantages of the prior art.

One aspect of the present disclosure is to provide a high-resolutionmicro-LED display device and a manufacturing method of the same that canreduce a production time period, increase production yield and lowermanufacturing costs.

Another aspect of the present disclosure is to provide a high-resolutionmicro-LED display device and a manufacturing method of the same that canminimize crack propagation to a micro LED, which may occur during theprocess of manufacturing a micro LED display device.

Another aspect of the present disclosure is to provide a high-resolutionmicro-LED display device and a manufacturing method of the same that canminimize a boundary area between micro LEDs.

Yet another aspect of the present disclosure is to provide ahigh-resolution micro-LED display device and a manufacturing method ofthe same that can minimize recognition of a boundary area between microLEDs by a user.

The present disclosure is not limited to what has been described.Additionally, other aspects and advantages that have not been mentionedmay be clearly understood from the following description and may be moreclearly understood from aspects. Further, it will be understood that theaspects and advantages of the present disclosure may be realized viameans and a combination thereof that are described in the appendedclaims.

A manufacturing method of a micro-LED display device according to thepresent disclosure is described as follows.

The manufacturing method may include forming a plurality of thin-filmtransistor arrays above a first substrate that is partitioned into aplurality of thin-film transistor array areas which include a pluralityof thin-film transistor areas, and forming a plurality of micro-LEDarrays above a second substrate that is partitioned into a plurality ofmicro-LED array areas which include a plurality of micro-LED areas.

Next, the manufacturing method may include transferring the micro-LEDarray that corresponds to the thin-film transistor array area onto thefirst substrate.

Next, the manufacturing method may include forming a third substrate anda bank film above the first substrate, and patterning the bank film toform—a first bank layer that corresponds to a boundary area betweenmicro-LED areas and a second bank layer that corresponds to an edge areaof a micro-LED array area, to form a pixel area and a pixel array arearespectively and to remove a bank film in a boundary area between secondbank layers adjacent to each other.

Next, the manufacturing method may include cutting the third substrateand the first substrate along a scribe zone that is set in a boundaryarea between the second bank layers adjacent to each other, andseparating a pixel array that includes the thin-film transistor arrayand the micro-LED array from the first substrate and transferring thepixel array onto a fourth substrate.

In the manufacturing method of a micro-LED display device according tothe present disclosure, micro LEDs may be transferred as the unit of apreset array area. Accordingly, unlike a method in which micro LEDs aretransferred individually, the manufacturing method makes it possible toreduce a production time period and increase production yield.

Additionally, in the manufacturing method of a micro-LED display deviceaccording to the present disclosure, a thin-film transistor layer, amicro LED layer and a bank film that correspond to a scribe zone may beremoved before the process of cutting. Accordingly, crack propagationthat may happen during the process of cutting may be minimized, and aboundary area between micro LEDs may be minimized.

A micro-LED display device according to the present disclosure mayinclude a lower substrate that defines a plurality of pixel array areaswhich include a plurality of pixel areas, a thin-film transistor arraythat is placed above the lower substrate and that includes a pluralityof thin-film transistors which correspond to each of the pixel areas, amicro-LED array that is placed above the thin-film transistor array andthat includes a plurality of micro LEDs which correspond to each of thepixel areas, an upper substrate that is placed above the micro-LEDarray, and a first bank layer that is placed in a boundary area betweenthe pixel areas and a second bank layer that is placed in an edge areaof the pixel array area, which are placed above the upper substrate.

In this case, the second bank layer is spaced a certain distance apartfrom an end of the upper substrate that corresponds to the pixel arrayarea.

As described above, the micro-LED display device according to thepresent disclosure may minimize cracks that can be directly propagatedthrough the second bank layer because the second bank layer is spaced acertain distance apart from an end of the upper substrate. Additionally,internal light may be re-reflected by a spaced part of the uppersubstrate. Thus, recognition of a boundary area by a user may beminimized.

According to the present disclosure, micro LEDs are not transferredindividually. Instead, micro LEDs may be transferred as the unit of apreset array area. Thus, a production time period may be reduced.Additionally, the unit of an array area may be set in different sizesand patterns. Accordingly, an area of a circular substrate, which is notused, may be minimized. Thus, production yield may be increased, andmanufacturing costs may be reduced.

According to the present disclosure, a thin-film transistor layer, amicro LED layer and a bank film that correspond to a scribe zone may beremoved before the process of cutting. Accordingly, direct crackpropagation through the layers and film during the process of cuttingmay be minimized, and a defect rate may be minimized. Additionally,because a second bank layer in an edge area of a pixel array area isspaced a certain distance apart from an end of an upper substrate.Accordingly, direct crack propagation through the second bank layerduring the process of cutting may be minimized, and a defect rate may beminimized.

According to the present disclosure, the thin-film transistor layer, themicro LED layer and the bank film that correspond to the scribe zone maybe removed before the process of cutting. Accordingly, a width of a deadzone for preventing damage done to elements, which may be caused by theprocess of cutting, may be minimized, a width of the second bank layermay be reduced, a gap between micro LEDs may be minimized, and highresolution may be implemented.

According to the present disclosure, a spaced part of the uppersubstrate, which is in a boundary area between micro LEDs, mayre-reflect light of the micro LEDs outward, which is reflected inward bya cover layer. Thus, the boundary area between the micro LEDs recognizedby a user may be minimized.

Specific effects of the present disclosure together with theabove-described effects are described in the following detaileddescription of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate aspects of the disclosure andtogether with the description serve to explain the principles of thedisclosure.

In the drawings:

FIG. 1 is a flow chart illustrating a manufacturing method of amicro-LED display device according to the present disclosure;

FIGS. 2A and 2B are a schematic plan view and a schematiccross-sectional view illustrating a process of forming a plurality ofthin-film transistor arrays on a first substrate;

FIGS. 3A and 3B are a schematic plan view and a schematiccross-sectional view illustrating a process of forming a micro-LED arrayon a second substrate;

FIGS. 4A and 4B are a schematic plan view and a schematiccross-sectional view illustrating a process of transferring a micro-LEDarray onto the first substrate;

FIGS. 5A and 5B are a schematic plan view and a schematic sectional viewillustrating a process of forming a third substrate and a bank film onthe first substrate;

FIGS. 6A and 6B are a schematic plan view and a schematic sectional viewillustrating a process of patterning the bank film;

FIGS. 7A and 7B are a schematic plan view and a schematic sectional viewillustrating a process of cutting the third substrate and the firstsubstrate;

FIG. 8 is a schematic plan view illustrating processes of separating apixel array from the first substrate and transferring the separatedpixel array onto a fourth substrate;

FIGS. 9A, 9B and 9C are schematic plan views illustrating variousexamples of a pixel array area that has various sizes and patterns; and

FIG. 10 is a cross-sectional view illustrating a partial area of amicro-LED display device according to the present disclosure.

DETAILED DESCRIPTION

The above-described features and advantages are specifically describedhereunder with reference to the attached drawings. Accordingly, onehaving ordinary skill in the art to which the present disclosurepertains may readily implement the technical spirit of the presentdisclosure. Further, in describing the present disclosure,publicly-known technologies in relation to the disclosure are notspecifically described if they are deemed to make the gist of thedisclosure unnecessarily vague. Below, aspects are described withreference to the attached drawings. In the drawings, identical referencenumerals denote identical or similar elements.

When any element is described as being “on (or under)” an element, or“above (or below)” an element, any element may be directly on (ordirectly under) the element, and an additional element may be interposedbetween the element and any element that is placed above (or below) theelement.

It should be further understood that when an element is described asbeing “connected”, “coupled” or “connected” to another element, theelement may be directly connected or may be able to be directlyconnected to another element. However, it is also to be understood thatan additional element may be “interposed” between the two elements, orthe two elements may be “connected”, “coupled” or “connected” through anadditional element.

FIG. 1 is a flow chart illustrating a manufacturing method of amicro-LED display device 10 according to the present disclosure.

First, a plurality of thin-film transistor arrays 120 may be formed on afirst substrate 100 (shown in FIG. 2A) that is partitioned into aplurality of thin-film transistor array areas (TAA) which includes aplurality of thin-film transistor areas (TA), and a plurality ofmicro-LED arrays 220 (shown in FIG. 3B) may be formed on a secondsubstrate 200 (shown in FIG. 3A) that is partitioned into a plurality ofmicro-LED array areas (MAA) which includes a plurality of micro-LEDareas (MA) (S101-1, and S101-2).

Next, the micro-LED array 220 that corresponds to the thin-filmtransistor array area (TAA) may be transferred onto the first substrate100 (S102).

Next, a third substrate 300 and a bank film 310 may be formed over thefirst substrate 100 (S103).

Next, the bank film 310 may be patterned to form a first bank layer 311that corresponds to a boundary area between the micro-LED areas (MA) anda second bank layer 312 that corresponds to an edge area of themicro-LED array area (MAA), to form a pixel area (PA) and a pixel arrayarea (PAA) respectively, and to remove the bank film 310 in a boundaryarea between the second bank layers 312 adjacent to each other (S104).

Next, the third substrate 300 and the first substrate 100 may be cutalong a scribe zone (SZ) that is set in a boundary area between thesecond bank layers 312 adjacent to each other (S105).

Next, a pixel array that includes the thin-film transistor array 120 andthe micro-LED array 220 is separated from the first substrate 100 and istransferred onto a fourth substrate 400. Thus, a micro-LED displaydevice 10 may be manufactured (S106).

Below, a manufacturing method of a micro-LED display device according tothe present disclosure is specifically described, based on theabove-described manufacturing order.

In the following description, the process of photolithography includingdeposition, photoresist (PR) coating, exposure, development, etching,and photoresist (PR) stripping may be used to pattern each of the layersand films. The process of photolithography is known to one havingordinary skill in the art. Accordingly, description of the process isavoided. For instance, in deposition, the process of sputtering may beused for a metallic material, and the process of plasma enhanced vapordeposition (PECVD) may be used for a semiconductor or an insulationfilm. Also, in etching, dry etching and wet etching may be optionallyused on the basis of materials. Technologies that are used by one havingordinary skill in the art may be applied.

FIGS. 2A and 2B a schematic plan view and a schematic cross-sectionalview illustrating a process of forming a plurality of thin-filmtransistor arrays 120 on the first substrate 100.

A thin-film transistor layer may be formed over a first substrate 100such that a plurality of thin-film transistor array areas (TAA)including a plurality of thin-film transistor arrays (TA) ispartitioned. That is, a plurality of thin-film transistors 110 may forma single thin-film transistor array 120.

The thin-film transistor layer may include a buffer layer 111 that isformed over the entire surface of the first substrate 100, a gateelectrode 112 that is formed on the buffer layer 111, a gate insulationlayer 113 that is formed over the entire surface of the first substrate100 to cover the gate electrode 112, a semiconductor layer 114 that isformed on the gate insulation layer 113, and a first electrode 115 a anda second electrode 115 b that are formed on the semiconductor layer 114.

Thin-film transistors (TFT) 110 may be formed to correspond to each ofthe thin-film transistor arrays (TA), and may operate as a drivingelement that can drive a micro LED 210.

The thin-film transistor layer that corresponds to a boundary areabetween the thin-film transistor array areas (TAA) which are adjacent toeach other may be removed through the process of patterning usingetching. In this case, the removed thin-film transistor layer may be thebuffer layer 111 and the gate insulation layer 113 that are formed overthe entire surface of the first substrate 100.

Accordingly, the thin-film transistor array areas (TAA) that areadjacent to each other may be respectively partitioned, may not beconnected to each other, and may be physically divided.

Specifically, in the plurality of thin-film transistor array areas (TAA)above the first substrate 100, the thin-film transistor layer may bepatterned along a pattern of each of the thin-film transistor arrayareas (TAA). Accordingly, each of the thin-film transistor array areas(TAA) may be configured to separate in the shape of an island.

A size and pattern of the thin-film transistor array area (TAA) may bepreset through design. Specifically, the size and pattern of thethin-film transistor array area (TAA) may be preset to correspond to thesize and pattern a pixel array area (PAA) of the micro-LED displaydevice 10, which is finally transferred to form the micro-LED displaydevice 10.

Accordingly, the size and pattern of the plurality of thin-filmtransistor array areas (TAA) above the same first substrate 100 may bethe same. However, each of the plurality of thin-film transistor arrayareas (TAA) may be set to have a different size and pattern in advance,and the size and pattern of the plurality of thin-film transistor arrayareas (TAA) vary depending on the size and pattern of the pixel arrayarea (PAA) of the micro-LED display device 10, which is finally formed.

A sapphire substrate or a silicon substrate may be used as the firstsubstrate 100. However, the first substrate 100 is not limited.

FIGS. 3A and 3B are a schematic plan view and a schematiccross-sectional view illustrating a process of forming a micro-LED array220 on a second substrate 200.

A micro-LED layer may be formed on the second substrate 200 such that aplurality of micro-LED array areas (MAA) including a plurality ofmicro-LED areas (MA) is partitioned.

That is, a plurality of micro LEDs 210 may form a single micro-LED array220, as illustrated in FIG. 3A.

The micro LED 210 may have a structure in which an undoped GaN bufferlayer 211 and an n-type GaN layer 212 are formed over the entire surfaceof the second substrate 200, and an active layer 213 with a multiquantum well (MQW) structure and a p-type GaN layer 214 are stacked onthe undoped GaN buffer layer 211 and the n-type GaN layer 212.

The micro LEDs 210 may be configured to correspond to each of themicro-LED areas (MA) and may respectively operate as a light-emittingelement that emits light. In the present disclosure, the micro LED 210that emits blue light is used. However, the micro LED 210 is not limitedto what has been described, and micro LEDs 210 that respectively emitred light, green light, and blue light may be used.

The micro-LED layer that corresponds to a boundary area between themicro-LED array areas (MAA) adjacent to each other may be removedthrough the process of patterning using etching. In this case, theremoved micro-LED layer may be the undoped GaN buffer layer 211 and then-type GaN layer 212 that are formed over the entire surface of thesecond substrate 200.

Accordingly, the micro-LED array areas (MAA) adjacent to each other maybe respectively partitioned, may not be connected to each other, and maybe physically divided.

Specifically, in the plurality of micro-LED array areas (MAA) on thesecond substrate 200, the micro-LED layer may be patterned along apattern of each of the micro-LED array areas (MAA). Accordingly, each ofthe micro-LED array areas (MAA) may be configured to separate in theshape of an island.

The size and pattern of the micro-LED array areas (MAA) may be setthrough design in advance. Specifically, the size and pattern of themicro-LED array area (MAA) may be set in advance to correspond to thepixel array area (PAA) of the micro-LED display device 10, which isfinally transferred to form the micro-LED display device 10.

Accordingly, the size and pattern of the plurality of micro-LED arrayareas (MAA) above the same second substrate 200 may be the same.However, each of the plurality of micro-LED array areas (MAA) may be setto have a different size and pattern in advance, and the size andpattern of the plurality of micro-LED array areas (MAA) vary dependingon the size and pattern of the pixel array area (PAA) of the micro-LEDdisplay device 10 that is finally formed.

That is, the size and pattern of the micro-LED array area (MAA) maycorrespond to the size and pattern of the above-described thin-filmtransistor array area (TAA) in the same manner.

A buffer layer is formed on the second substrate 200, and then a GaNthin film is grown above the buffer layer. By doing so, the micro LED210 may be formed. In this case, sapphire, silicon (Si), GaN, siliconcarbide (SiC), gallium arsenide (GaAs), zinc oxide (ZnO) and the likemay be used for the second substrate 200 for growing the GaN thin film.However, materials for the second substrate are not limited to what hasbeen described.

Specifically, the micro LED 210 is formed by crystallizing an inorganicmaterial such as GaN on a semiconductor substrate. The process ofcrystallization may be commonly referred to as epitaxy, epitaxial growthor epitaxial processing.

FIGS. 4A and 4B are a schematic plan view and a schematiccross-sectional view illustrating a process of transferring themicro-LED array 220 onto the first substrate 100.

Sizes and patterns of the thin-film transistor arrays 120 and themicro-LED arrays 220 are set in advance on the basis of a size and apattern of a pixel array of a micro-LED display device 10 that isfinally formed. Accordingly, the thin-film transistor arrays 120 thathave a size and a pattern corresponding to those of the micro-LED arrays220 are placed on the first substrate 100.

Thus, the micro-LED array 220 that has a size and pattern correspondingto a size and pattern of a thin-film transistor array area (TAA) isseparated from a second substrate 200, and the separated micro-LED array220 may be transferred onto the first substrate 100.

When a size of the first substrate 100 above which the thin-filmtransistor arrays 120 are placed is larger than a size of the secondsubstrate 200 above which the micro-LED arrays 220 are placed, aplurality of second substrates 200 may be used to allow all themicro-LED arrays 220 of the first substrate 100 to correspond to thethin-film transistor arrays 120.

A laser lift-off (LLO) method may be used as a method for separating themicro-LED arrays 200 from the second substrate 200. However, variousseparation methods may be used.

A transfer method using polydimethylsiloxane (PDMS) may be used as amethod for transferring the separated micro-LED arrays 200 onto thefirst substrate 100. However, various separation methods may be used.

FIGS. 5A and 5B are a schematic plan view and a schematiccross-sectional view illustrating a process of forming a third substrate300 and a bank film 310 on the first substrate 100.

A third substrate 300 may be formed on the thin-film transistor arrays120 and the micro-LED arrays 200 that are formed on the first substrate100, and a bank film 310 may be formed to cover the entire surface ofthe third substrate 300.

The bank film 310 may include an organic material or an inorganicmaterial, and a material of the bank film 310 is not limited. When thebank film is configured to have a thick thickness, an organic materialmay be used.

In this case, the buffer film 301 may be additionally formed between thebank film 310 and the third substrate 300. An inorganic material may beused for the buffer film 301.

FIGS. 6A and 6B are a schematic plan view and a schematic sectional viewillustrating a process of patterning the bank film 310.

The bank film 310 may be patterned and may consist of a first bank layer311 that corresponds to a boundary area between micro-LED arrays (MA),and a second bank layer 312 that corresponds to an edge area of amicro-LED array area (MAA).

Specifically, the bank film 310 that corresponds to the boundary areabetween micro-LED arrays (MA) is left, and the bank film 310 thatcorresponds to the micro-LED array (MA) is removed. Accordingly, an areathat corresponds to the micro-LED array (MA) may have an opening.

That is, the bank film 310 that corresponds to the boundary area betweenmicro-LED arrays (MA) may be the first bank layer 311, and an area thatcorresponds to the opening formed between the first bank layers 311 maybe defined as a pixel area (PA).

A single pixel area (PA) may include a single thin-film transistor 110,a single micro-LED 210, and an opening that is formed by the first banklayers 311.

After the bank film 310 is patterned, a color filter layer 320 may beadditionally formed in each pixel area (PA).

That is, a color filter layer 320 may be formed in each opening that isformed by the first bank layers 311 and may be included in the pixelarea (PA). Accordingly, light of a color desired by a user may beimplemented.

A usual color filter film may be used as the color filter layer 320, anda quantum dot film may be formed with an inkjet method to form the colorfilter layer 320. However, a forming process of the color filter layer320 is not limited.

For instance, a micro LED 210 that emits blue light may be used inpresent disclosure. In this case, the color filter layer 320 may beformed in pixel areas (PA) for implementing red and green to implementred and green, and a micro LED 210 that emits blue light may be usedwith no additional color filter layer 320 in pixel areas (PA) forimplementing blue.

The bank film 310 that corresponds to the edge area of the micro-LEDarray area (MAA) may be the second bank layer 312.

The second bank layer 312 is configured to encircle the edge area of themicro-LED array area (MAA). Accordingly, the second bank layer 312 mayserve as a boundary between the micro-LED array areas (MAA). Thus, apixel array area (PAA) may be defined.

The second bank layer 312 may be patterned in the same form as the firstbank layer 311.

Specifically, the bank film 310 that corresponds to an edge area of themicro-LED array area (MAA) is left, and the bank film 310 thatcorresponds to the micro-LED area (MA) is removed except the first banklayer 311. Thus, the second bank layer 312 may be formed.

Like the area between the first bank layers 311, an area between thefirst bank layer 311 and the second bank layer 312 may be defined as apixel area (PA) and may have an opening from which the bank film 310 isremoved. Accordingly, a color filter layer 320 may also be formed in theopening in the pixel area (PA) between the first bank layer 311 and thesecond bank layer 312.

Additionally, the bank film 310 according to an aspect of the presentdisclosure may be patterned with the method of etching such that thebank films 310 not only in the area that corresponds to the pixel area(PA) but also in the boundary area between the second bank layers 312adjacent to each other are removed.

As described above, the second bank layer 312 may serve as a boundarybetween the micro-LED array areas (MAA) and may also serve as a boundarybetween the pixel array areas (PAA).

That is, a boundary area exists among pixel array areas (PAA). Duringthe process of patterning for forming the first bank layer 311 and thesecond bank layer 312, the bank film 310 that corresponds to theboundary area is removed. Accordingly, an opening is formed in aboundary area between second bank layers 312 adjacent to each other.

The opening formed in the boundary area between second bank layers 312adjacent to each other may be configured to match an area which isplaced below the opening and in which a thin-film transistor layer isremoved in the boundary area between thin-film transistor array areas(TAA) adjacent to each other, and an area which is placed below theopening and in which a micro-LED layer is removed in the boundary areabetween micro-LED array areas (MAA) adjacent to each other.

Accordingly, a third substrate 300 from which a micro-LED layer isremoved, and a first substrate 100 from which a thin-film transistorlayer is removed may be placed below the opening that is formed in theboundary area between the second bank layers 312 adjacent to each other.

When a buffer film 301 is formed between the third substrate 300 and thebank film 310, the buffer film 301 may also be patterned to correspondto the opening formed in the boundary area between the second banklayers 312 adjacent to each other, and may be formed as a buffer layer302 of the third substrate corresponding to each of the pixel arrayareas (PAA).

The boundary area between the second bank layers 312 adjacent to eachother may match a scribe zone (SZ) that is defined during a process ofcutting the third substrate 300, which is performed in the next step.However, the boundary area may be wider than the scribe zone (SZ).

The first bank layer 311 and the second bank layer 312 may be used as awall that serves as a boundary to form each pixel area (PA) and eachpixel array area (PAA), and may prevent different colors of light raysthat are emitted from each pixel area (PA) from being mixed.

FIGS. 7A and 7B are a schematic plan view and a schematiccross-sectional view illustrating a process of cutting the thirdsubstrate 300 and the first substrate 100.

As illustrated in FIGS. 7A and 7B, the third substrate 300 and the firstsubstrate 100 may be laser-cut along a scribe zone (SZ) that is set in aboundary area between second bank layers 312 adjacent to each other.

In this case, the scribe zone (SZ) may be configured to match theboundary area between second bank layers 312 adjacent to each other butmay be narrower than the boundary area, as described above.

When the laser-cutting is performed in the state in which the scribezone (SZ) is set to be the same as or narrower than the boundary areabetween second bank layers 312 adjacent to each other, the second banklayer 312, the micro-LED layer, and the thin-film transistor layer andthe scribe zone (SZ) are not overlapped, and the layers are not directlyaffected by laser-cutting. Thus, crack propagation to each element maybe minimized, thereby reducing a defect rate.

On the contrary, when laser-cutting is performed in the state in whichthe bank film 310, the micro-LED layer and the thin-film transistorlayer that correspond to the scribe zone (SZ) are not removed, the bankfilm 310, the micro-LED layer, and the thin-film transistor layers aredirectly affected by laser-cutting. Accordingly, a crack may bepropagated to elements such as the micro-LED 210 and the thin-filmtransistor 110, thereby increasing a defect rate.

Additionally, as a buffer area, a dead zone (DZ) that serves as a buffermaterial to minimize crack propagation is required to be set relativelywidely in advance in the bank film 310, the micro-LED layer, and thethin-film transistor layer.

That is, to minimize the effect of laser-cutting on the elements, a deadzone (DZ) that may serve as a buffer area may be set between theelements and the scribe zone (SZ). The dead zone (DZ) may be set betweenthe elements such as the second bank layer 312, the micro-LED layer, andthe thin-film transistor layer, and the scribe zone (SZ). Accordingly,the dead zone (DZ) may be formed along both lateral lines of the scribezone (SZ).

However, when the dead zone (DZ) of the second bank layer 312 isconfigured to be wide, the second bank layer 312 becomes wide.Accordingly, in a micro-LED display device 10 to which the pixel arrayis finally transferred, a gap between pixels that have the second banklayer 312 therebetween becomes wide.

Thus, high resolution may be hardly implemented due to a wider gapbetween pixels, and a wider boundary area may be recognized by a user.

However, when the boundary area that corresponds to the scribe zone (SZ)is patterned in advance by etching before the process of laser-cutting,as in an aspect of the present disclosure, the second bank layer 312,the micro-LED layer, and the thin-film transistor layer are not directlyaffected by the process of laser-cutting. Accordingly, crack propagationto each element may be minimized, and a defect rate may be decreased.

In an aspect of the present disclosure, the dead zone (DZ) that is abuffer area for minimizing crack propagation may be relatively narrow.

When the dead zone (DZ) is configured to be narrow as in the aspect, inthe micro-LED display device 10 to which the pixel array is finallytransferred, a distance among pixels that have the second bank layer 312therebetween may be as short as possible. Thus, high resolution may beimplemented, and recognition of the boundary area by a user may beminimized.

FIG. 8 is a schematic plan view illustrating processes of separating apixel array from a first substrate 100 and transferring the separatedpixel array onto a fourth substrate 400.

In the processes of FIGS. 7A and 7B, pixel arrays in each pixel arrayarea (PAA) are laser-cut in a predetermined size and pattern. The cutpixel arrays are transferred onto a fourth substrate 400 that is a basesubstrate of the micro-LED display device 10.

In this case, the pixel arrays are formed in a size and pattern thatcorrespond to a size and pattern of the pixel array area (PAA) formed inthe fourth substrate 400 from the step of forming a thin-film transistorarray area (TAA). Accordingly, the pixel arrays that are transferredonto the fourth substrate 400 may be finally transferred to match pixelarray areas (PAA) of a micro-LED display device 10 designed by a user.

In the fourth substrate 400, sizes and patterns of the pixel array area(PAA) that is designed by a user in advance may vary as illustrated inFIGS. 9A, 9B and 9C.

The size and pattern of the pixel arrays may vary, thereby increasing aproduction yield rate.

Specifically, when a circular silicon wafer substrate is used as thefirst substrate 100 and the second substrate 200, all the area of thecircular silicon wafer substrate may be hardly used like other circularsubstrates.

According to a manufacturing method for a micro-LED display device 10 ofan aspect, sizes and patterns of pixel arrays may vary. Thus, even whena circular silicon wafer substrate is used, processing is performed suchthat a wasted area may be minimized, thereby increasing a productionyield rate.

For instance, when pixel array areas (PAA) having a very large size arerequired, pixel arrays having a size that corresponds to a size of pixelarray areas (PAA) are formed on a substrate. Additionally, the rest areaof the substrate, except the area which is used by the pixel array areas(PAA) having a large size, may be used by pixel array areas (PAA) havinga small size.

Thus, pixel arrays of a large size may be formed, and pixel arrays of asmall size adequate for the rest area, except the area that is used bythe pixel arrays of a large size, may be additionally formed. Thus,almost all of the area of the substrate may be used for forming pixelarrays without being wasted.

The area of the substrate may be used as much as possible without beingwasted, thereby increasing a production yield rate and decreasingproduction costs.

In a manufacturing method for a micro-LED 210 display device accordingto an aspect, micro LEDs 210 are not individually transferred. Instead,as a unit, a micro-LED array 220 that includes a plurality of micro LEDs210, i.e., a pixel array, is transferred at a time, thereby improvingefficiency of processing and minimizing a gap between pixel areas (PA).

When micro LEDs 210 are cut and transferred one by one, each boundaryarea among the micro LEDs 210 is required to be cut. Accordingly, a banklayer that encircles each micro LED 210 may become thicker.

For instance, according to an aspect, the first bank layer 311 is formedto correspond to a boundary area between pixel areas (PA). A pixel arrayarea (PAA) that includes a plurality of pixel areas (PA) is cut andtransferred as a unit. Accordingly, a boundary area between pixel areas(PA) is not required to be cut. Thus, the first bank layer 311 may nothave a wide width.

On the contrary, when micro LEDs 210 are cut and transferred one by one,a boundary area between pixel areas (PA) is required to be cut.Accordingly, a width of a bank layer corresponding to the first banklayer 311 according to an aspect is required to be wide enough toinclude a dead zone (DZ) having a predetermined width.

Thus, a width of the bank layer that encircles each of the cut microLEDs 210 becomes wider, and a gap between pixel areas (PA) also becomeswider because a plurality of bank layers serve as a boundary betweenmicro LEDs 210.

In this case, the boundary area between pixel areas (PA) may berecognized by a user due to a wider gap between the pixel areas (PA).Additionally, when each of the micro LEDs 210 is cut, the bank layersthat encircle the micro LEDs 210 are cut. Accordingly, a crack is likelypropagated to elements adjacent to the bank layers, thereby increasingthe possibility of causing a defect in each micro LED 210.

However, according to the present disclosure, micro LEDs 210 are not cutand transferred one by one. Instead, a micro-LED array 220 that includesa plurality of micro LEDs 210 is cut and transferred as a unit. Thus,the possibility of crack propagation may be reduced, gaps among pixelareas (PA) may be minimized, high resolution may be implemented, andrecognition of a boundary area by a user may be minimized.

A plurality of pixel arrays are transferred onto the fourth substrate400, and pad units such as a gate pad unit or a readout integratedcircuit (ROIC) pad unit that can connect various signals and power tothe transferred pixel arrays, and cables may be formed in the fourthsubstrate 400, to constitute the micro-LED display device 10.

FIG. 10 is a cross-sectional view illustrating a partial area of amicro-LED display device 10 according to an aspect of the presentdisclosure.

The micro-LED display device 10 according to the present disclosure mayinclude a lower substrate 100 that defines a plurality of pixel arrayareas (PAA) which include a plurality of pixel areas (PA), a thin-filmtransistor layer that is placed above the lower substrate 100 and thatincludes a plurality of thin-film transistors 110 which correspond toeach of the pixel areas (PA), a micro-LED layer that is placed above thethin-film transistor layer and that includes a plurality of micro LEDs210 which correspond to each of the pixel areas (PA), an upper substrate300 that is placed above the micro-LED layer, and a first bank layer 311that is placed in a boundary area between the pixel areas (PA) and asecond bank layer 312 that is placed in an edge area of a pixel arrayarea (PAA), which are placed above the upper substrate 300. In thiscase, the second bank layer 312 may be spaced a certain distance apartfrom an end of the upper substrate 300 that corresponds to the pixelarray area (PAA).

Additionally, a cover layer 500 that is an outermost surface of themicro-LED display device 10 may be placed above the upper substrate 400,and a polarizing layer 510 may be placed below the cover layer 500.

The lower substrate 100 may be used as a thin-film transistor arraysubstrate, and glass or plastic materials may be used for the lowersubstrate 100. Additionally, a flexible substrate that consists of aplastic material having flexibility such as polyimide may be used as thelower substrate 100.

A plurality of pixel array areas (PAA) that include a plurality of pixelareas (PA) are defined above the lower substrate 100.

Specifically, each of the thin-film transistors 110 is formed tocorrespond to each of the pixel areas (PA) in each pixel area (PA). Aplurality of thin-film transistors 110 that are formed as describedabove are gathered. By doing so, a thin-film transistor array 120 thatcorresponds to the pixel array area (PAA) may be formed.

Thin-film transistor arrays 120 may be formed in the state of beingseparated from one another in boundary areas among pixel array areas(PAA). The thin-film transistor arrays 120 may be physically separatedfrom one another but may be electrically connected to one another byvarious cables that are formed above the lower substrate 100.

Specifically, a buffer layer 111 may be first formed above the lowersubstrate 100. SiO2 may be used for the buffer layer 111 and the bufferlayer 111 may be formed in a single layer or in multiple layers.

The buffer layer 111 that is configured to cover all the plurality ofpixel areas (PA) may be configured to cover the lower substrate 100 thatcorresponds to a single pixel array area (PAA).

The buffer layers 111 in pixel array areas (PAA) adjacent to each othermay be separated from each other along a boundary area between the pixelarray areas (PAA).

A thin-film transistor 110 may be formed above the buffer layer 111. Thethin-film transistor 110 may include a gate electrode 112 that is formedabove the lower substrate, a gate insulation layer 113 that is formedover a whole surface of the lower substrate 100 to cover the gateelectrode 112, a semiconductor layer 114 that is formed above the gateinsulation layer 113, and a first electrode 115 a and a second electrode115 b that are formed above the semiconductor layer 114.

The gate electrode 112 may consist of a metallic material such as Cr,Mo, Ta, Cu, Ti, and Al, or an alloy thereof but is not limited.

The gate insulation layer 113 may be formed to cover the gate electrode112 over the whole surface of the lower substrate 100 above the gateelectrode 112. Accordingly, the gate insulation layer 113 may cover allthe gate electrodes 112 of the plurality of thin-film transistors 110that correspond to the plurality of pixel areas (PA).

That is, the gate insulation layer 113 that is configured to cover allthe plurality of pixel areas (PA) may be configured to cover the lowersubstrate 100 that corresponds to a single pixel array area (PAA).

However, gate insulation layers 113 in pixel array areas (PAA) adjacentto each other may be separated from each other along a boundary areabetween the pixel array areas (PAA).

The gate insulation layer 113 may be formed in a single layer thatconsists of an inorganic material such as SiOx and SiNx, or in multiplelayers that include SiOx and SiNx.

The semiconductor layer 114 may be formed above the gate insulationlayer 113. The semiconductor layer 114 may consist of an amorphoussemiconductor such as amorphous silicon and may consist of an oxidesemiconductor such as IGZO (Indium Gallium Zinc Oxide), TiO2, ZnO, WO₃,and SnO₂, but is not limited.

The first electrode 115 a and the second electrode 115 b that areconnected with the semiconductor layer 114 may be formed above thesemiconductor layer 114. The first electrode 115 a may be a sourceelectrode, and the second electrode 115 b may be a drain electrode.However, the source electrode and the drain electrode may be exchangedon the basis of a direction of electric currents. The first electrode115 a and second electrode 115 b may consist of a metallic material suchas Cr, Mo, Ta, Cu, Ti, and Al, or an alloy thereof but is not limited.

In the present disclosure, a bottom gate-type thin-film transistor inwhich a gate electrode 112 is placed below a semiconductor layer 114 isdescribed as an example. However, the thin-film transistor 110 is notlimited to what has been described. Various types of thin-filmtransistors such as a top gate-type thin-film transistor 110 may beapplied.

A micro LED 210 that corresponds to a pixel area (PA) may be formedabove the thin-film transistor 110. An insulation layer may be placedbetween each thin-film transistor 110 and each micro LED 210. In thiscase, the insulation layer may be formed in a single organic layer thatconsists of an organic material such as photoacryl or in a singleinorganic layer that consists of an inorganic material, and may beformed in multiple layers that consist of organic and inorganicmaterials.

The thin-film transistor 110 may be electrically connected with themicro LED 210 through a third electrode 117 and may serve as a drivingelement that drives the micro LED 210. A method of connecting thethin-film transistor 110 and the micro LED 210 is not limited. Thethin-film transistor 110 and the micro LED 210 may be connected usingvarious methods.

The micro LED 210 may have a structure in which an undoped GaN bufferlayer 211, an n-type GaN layer 212, an active layer 213 having a multiquantum well (MQW) structure, and a p-type GaN layer 214 are stacked.

Additionally, an ohmic contact layer that is placed above the p-type GaNlayer 214, a p-type electrode that contacts a part of the ohmic contactlayer, and an n-type electrode that contacts a part of the n-type GaNlayer 212 which is exposed by etching a part of the active layer 213,the p-type GaN layer 214 and the ohmic contact layer may be furtherformed in the micro LED 210.

The n-type GaN layer 212 is a layer for providing electrons to theactive layer 213. The n-type GaN layer 212 may be formed by dopingn-type impurities such as silicon to a GaN semiconductor layer.

The active layer 213 is a layer that emits light by coupling of injectedelectrons and holes. In the multi quantum well structure of the activelayer 213, a plurality of barrier layers and a plurality of well layersare alternately arranged. The well layer may consist of InGaN, and thebarrier layer may consist of GaN but are not limited to what has beendescribed.

The p-type GaN layer 214 is a layer for injecting holes to the activelayer 213. The p-type GaN layer 214 may be formed by doping p-typeimpurities such as Mg, Zn and Be to a GaN semiconductor layer.

The ohmic contact layer is a layer for allowing the p-type GaN layer 214to ohmically contact the p-type electrode. Transparent metal oxides suchas indium tin oxide (ITO), indium gallium zinc oxide (IGZO), and indiumzinc oxide (IZO) may be used for the ohmic contact layer.

The p-type electrode and n-type electrode may be formed in a singlelayer or in multiple layers that consist of at least one of metallicmaterials including Ni, Au, Pt, Ti, Al, and Cr, or an alloy thereof.

In the micro LED 210 with the structure, as a voltage is applied to thep-type electrode and n-type electrode, electrons and holes arerespectively injected from the n-type GaN layer 212 and the p-type GaNlayer 214 to the active layer 213. Then excitons are generated in theactive layer 213. As the excitons are decayed, light that corresponds toa difference in energy of a lowest unoccupied molecular orbital (LUMO)and a highest occupied molecular orbital (HOMO) of a light-emittinglayer is generated and emitted outward.

In this case, wavelengths of light that is emitted from the micro LED210 may be adjusted by adjusting a thickness of the barrier layer of themulti quantum well structure of the active layer 213. In the presentdisclosure, a micro LED 210 that emits blue light is used. However, themicro LED 210 is not limited to what has been described.

The structure of the micro LED 210 according to the present disclosureis not limited to a specific structure. Micro LEDs 210 with variousstructures such as a vertically structured micro LED and a horizontallystructured micro LED may be applied.

An upper substrate 300 may be formed above the micro LED layer thatincludes a plurality of micro LEDs 210. In this case, the uppersubstrate 300 is formed to have a size and patterns that correspond to asize and pattern of each of the pixel array areas (PAA). Accordingly,upper substrates 300 in the pixel array areas (PAA) adjacent to eachother may be spaced apart from each other with a boundary area betweenthe upper substrates 300.

A first bank layer 311 in a boundary area between pixel areas (PA), anda second bank layer 312 in an edge area of the pixel array area (PAA)may be placed above the upper substrate 300.

A buffer layer 302 of a third substrate may be formed between the uppersubstrate 300, and the first bank layer 311 and the second bank layer312. In this case, the buffer layer 302 of the third substrate may beformed along a whole surface of the upper substrate 300 to correspond toa single pixel array area.

The bank layers may be used as a wall that serves as a boundary to formeach pixel area (PA) and each pixel array area (PAA), and may preventdifferent colors of light rays that are emitted from each pixel area(PA) from being mixed.

In this case, the second bank layer 312 may be spaced a certain distanceapart from an end of the upper substrate 300 that corresponds to thepixel array area (PAA).

That is, in the micro LED display device 10 according to the presentdisclosure, the second bank layer 312 above the upper substrate 300 isnot matched with the end of the upper substrate 300 but is spaced acertain distance apart from the end of the upper substrate 300.Accordingly, the second bank layer 312 does not correspond to a scribezone (SZ), thereby minimizing crack propagation that may happen during aprocess of cutting the upper substrate 300 and bank film 310.

Specifically, in the micro-LED display device 10 according to thepresent disclosure, pixels that correspond to each pixel area (PA) arenot respectively cut and transferred to the lower substrate 100.Instead, each pixel array that includes a plurality of pixels is cut andtransferred. In this case, a structure for minimizing crack propagationparticularly in boundary areas among pixel arrays may be required.

The end of the upper substrate 300 corresponds to a boundary part of thescribe zone (SZ) that is cut in the laser-cutting process. Accordingly,when the second bank layer 312 is configured to match the end of theupper substrate 300, a crack may is propagated through the second banklayer 312 during the process of cutting the upper substrate 300 and mayaffect a micro LED element, a thin-film transistor element and the likein the pixel area (PA).

According to the present disclosure, the second bank layer 312 may bespaced a certain distance apart from the end of the upper substrate 300and may be spaced a certain distance apart from the boundary part of thescribe zone (SZ), thereby minimizing the effect of a crack, which ispropagated through the second bank layer 312 during the process ofcutting the upper substrate 300, on a micro LED element, a thin-filmtransistor element and the like in the pixel area (PA).

Additionally, the buffer layer 302 of the third substrate may be removedto match an end of the second bank layer 312. Accordingly, the bufferlayer 302 of the third substrate does not correspond to the scribe zone,thereby minimizing the effect of a crack, which is propagated throughthe buffer layer 302 of the third substrate during the process ofcutting the upper substrate 300, on a micro LED element, a thin-filmtransistor element and the like in the pixel area (PA).

According to the present disclosure, the second bank layer 312 is spaceda certain distance apart from the end of the upper substrate 300.Accordingly, the second bank layer 312 is not formed at the end of theupper substrate 300, and a spaced part 330 that is exposed to theoutside is formed at the end of the upper substrate 300.

Light that is emitted in the pixel area (PA) is reflected inward by acover layer 500, and the spaced part 330 may re-reflect reflected lightof the micro LED 210 outward. Accordingly, the spaced part 330 has theeffect of emitting light in the boundary area without an additionallight source such as the micro LED 210. As a result, recognition ofboundary areas among micro LEDs 210 by a user may be minimized.

Specifically, light is not emitted in the boundary area because a microLED 210 is not placed in a boundary area between micro LEDs 210. In thiscase, a user may recognize the boundary area from the outside.Accordingly, light is required to be sent to the boundary area as muchas possible such that the user may not recognize the boundary area fromthe outside.

However, according to the present disclosure, the spaced part 330 of theupper substrate 300 in a boundary area between micro LEDs 210 mayre-reflect light, reflected inward by the cover layer 500, outward.Accordingly, the spaced part 330 may perform the function that emitslight in the boundary area, thereby minimizing recognition of theboundary area between micro LEDs 210 by a user.

According to the present disclosure, micro LEDs 210 are not transferredone by one. Instead, as a unit, a micro-LED array 220 that includes aplurality of micro LEDs 210, i.e., a pixel array, is transferred at atime, thereby minimizing a distance among pixel areas (PA).

Accordingly, a distance between the micro LEDs 210 that have the firstbank layer 311 therebetween may be shorter than a distance between themicro LEDs 210 that have the second bank layer 312 therebetween.

For instance, the first bank layer 311 according to an aspect is formedto correspond to a boundary area between pixel areas (PA), and a pixelarray area (PAA) that includes a plurality of pixel areas (PA) is cutand transferred as a unit. Accordingly, the boundary area between pixelareas (PA) is not required to be cut, and the first bank layer 311 isnot required to have a wide width.

When the micro LEDs 210 are cut and transferred one by one, a boundaryarea between pixel areas (PA) is required to be cut. Accordingly, a banklayer is required to have a wide width to include a dead zone (DZ)having a predetermined width.

Thus, a width of the bank layer that encircles each of the cut microLEDs 210 becomes wide, and a gap between pixel areas (PA) becomes widebecause a plurality of bank layers serve as a boundary between microLEDs 210.

In this case, the boundary area between pixel areas (PA) may berecognized by a user due to a wider gap between the pixel areas (PA).Additionally, when each of the micro LEDs 210 is cut, the bank layersthat encircle the micro LEDs 210 are cut. Accordingly, a crack is likelypropagated to elements adjacent to the bank layers, thereby increasingthe possibility of causing a defect in micro LEDs 210.

However, according to an aspect of the present disclosure, micro LEDs210 are not cut and transferred one by one. Instead, a micro-LED array220 that includes a plurality of micro LEDs 210 is cut and transferredas a unit. Thus, the possibility of crack propagation may be reduced,gaps among pixel areas (PA) may be minimized, recognition of a boundaryarea by a user may be minimized, and high resolution may be implemented.

The first bank layer 311 and second bank layer 312 may have an inclinedsurface that faces toward a direction in which the micro LED 210 emitslight. Accordingly, luminous efficiency of the micro LED 210 mayimprove.

Additionally, surfaces on which adjacent second bank layers 312 faceeach other may also be inclined surfaces that faces toward a directionin which the micro LED 210 emits light. Accordingly, luminous efficiencyof the micro LED 210 may improve further.

Specifically, an additional micro LED 210 is not placed in an areabetween second bank layers 312 adjacent to each other. However, whenlight of the micro LED 210, which is emitted in the pixel area (PA),reflects from the cover layer 500 above the micro LED 210 and comes intothe micro-LED display device, the light may be re-reflected outward bythe inclined surfaces of the second bank layers 312.

The plurality of pixel array areas (PAA) of the micro LED display device10 according to the present disclosure may have the same size andpattern. However, the pixel array areas (PAA) may have different sizesand patterns by proving a different size to at least one pixel arrayarea (PAA).

A color filter layer 320 that corresponds to the pixel area (PA) may beplaced above the upper substrate 300.

That is, the color filter layer 320 may be formed in each of theopenings that are formed by the first bank layers 311 and may beincluded in the pixel area (PA). Accordingly, the color filter layer 320may emit light of a color desired by a user.

A usual color filter film may be used as the color filter layer 320, anda quantum dot film may be formed with an inkjet method to form the colorfilter layer 320. However, the color filter layer 320 is not limited.

For instance, a micro LED 210 that emits blue light may be used in anaspect. In this case, the color filter layer 320 may be formed in pixelareas (PA) for implementing red and green to implement red and green,and a micro LED 210 that emits blue light may be used with no additionalcolor filter layer 320 in pixel areas (PA) for implementing blue.

Additionally, a pad area may be formed above the lower substrate 100except the pixel array area (PAA), and a pad unit 410 that includesvarious connection cables and the like may supply various signals andvoltages to the pixel area (PA).

The present disclosure has been described with reference to the attacheddrawings. However, the present disclosure should not be construed asbeing limited to the aspects and drawings set forth herein.Additionally, it will be apparent that the disclosure may be modified indifferent forms by one having ordinary skill in the art within thetechnical spirit of the present disclosure. Further, although effects ofconfigurations of the present disclosure are not described explicitly indescription of the aspects, expected effects based on the configurationsshould be included in the scope of the present disclosure.

What is claimed is:
 1. A manufacturing method of a micro-LED displaydevice, comprising: forming a plurality of thin-film transistor arrayareas that includes a plurality of thin-film transistor arrays on afirst substrate; forming a plurality of micro-LED array areas thatincludes a plurality of micro-LED arrays on a second substrate;transferring the plurality of micro-LED array areas that correspond tothe plurality of thin-film transistor array areas onto the firstsubstrate; forming a bank film on a third substrate over the firstsubstrate; patterning the bank film to form a first bank layer thatcorresponds to a boundary area between the plurality of micro-LED arraysand a second bank layer that corresponds to an edge area of theplurality of micro-LED array areas, to form a pixel area and a pixelarray area, and to remove the bank film in a boundary area between thesecond bank layers adjacent to each other; cutting the third substrateand the first substrate along a scribe zone that is set in a boundaryarea between the second bank layers adjacent to each other; andseparating a plurality of pixel arrays that includes the plurality ofthin-film transistor arrays and the plurality of micro-LED arrays fromthe first substrate and transferring the plurality of pixel arrays ontoa fourth substrate.
 2. The manufacturing method of a micro-LED displaydevice of claim 1, further comprising removing a thin-film transistorlayer that corresponds to a boundary area between the plurality ofthin-film transistor array areas adjacent to each other, and removing amicro-LED layer that corresponds to a boundary area between theplurality of micro-LED array areas adjacent to each other before theforming of the plurality of thin-film transistor array areas and theforming of the plurality of micro-LED array areas respectively includes.3. The manufacturing method of a micro-LED display device of claim 2,wherein the bank layer, the thin-film transistor layer, and themicro-LED layer are removed by etching.
 4. The manufacturing method of amicro-LED display device of claim 1, wherein a size and pattern of theplurality of thin-film transistor array areas is the same as a size andpattern of the plurality of micro-LED array areas.
 5. The manufacturingmethod of a micro-LED display device of claim 1, wherein the cutting thethird substrate and the first substrate is performed by a laser.
 6. Themanufacturing method of a micro-LED display device of claim 1, whereinthe boundary area between the second bank layers adjacent to each otherhas a width greater than a width of the scribe zone.
 7. Themanufacturing method of a micro-LED display device of claim 1, whereinat least one of the plurality of pixel arrays has a different size. 8.The manufacturing method of a micro-LED display device of claim 1,further comprising forming a color filter layer in each of the pluralityof pixel arrays over the third substrate after the patterning the bankfilm.
 9. A micro-LED display device comprising: a lower substrate wherea plurality of pixel array areas that include a plurality of pixelarrays is defined; a thin-film transistor array placed over the lowersubstrate and including a plurality of thin-film transistors whichcorrespond to each of the plurality of pixel arrays; a micro-LED arrayplaced over the thin-film transistor array and including a plurality ofmicro LEDs which correspond to each of the plurality of pixel arrays; anupper substrate placed over the micro-LED array; and a first bank layerplaced in a boundary area between the plurality of pixel arrays and asecond bank layer placed in an edge area of the plurality of pixel arrayareas, which are placed over the upper substrate, wherein the secondbank layer is spaced apart from an end of the upper substrate thatcorresponds to the plurality of pixel arrays.
 10. The micro-LED displaydevice of claim 9, wherein a distance between the micro LEDs that havethe first bank layer therebetween is shorter than a distance between themicro LEDs that have the second bank layer therebetween.
 11. Themicro-LED display device of claim 9, wherein the first bank layer andthe second bank layer have an inclined surface that faces a direction inwhich the micro LED emits light.
 12. The micro-LED display device ofclaim 9, wherein adjacent two second bank layers face each other have asurface that is inclined to face a direction in which the micro LEDemits light.
 13. The micro-LED display device of claim 9, wherein atleast one of the plurality of pixel array areas has a different size.14. The micro-LED display device of claim 9, further comprising a colorfilter layer that corresponds to the pixel area is placed over the uppersubstrate.
 15. A manufacturing method of a micro-LED display device,comprising: removing a thin-film transistor layer that corresponds to aboundary area between a plurality of thin-film transistor array areas tobe formed; removing a micro-LED layer that corresponds to a boundaryarea between a plurality of micro-LED array areas to be formed; formingthe plurality of thin-film transistor array areas that includes aplurality of thin-film transistor arrays on a first substrate; formingthe plurality of micro-LED array areas that includes a plurality ofmicro-LED arrays on a second substrate; transferring the plurality ofmicro-LED array areas that correspond to the plurality of thin-filmtransistor array areas onto the first substrate; forming a bank film ona third substrate over the first substrate; patterning the bank film toform a first bank layer that corresponds to a boundary area between theplurality of micro-LED arrays and a second bank layer that correspondsto an edge area of the plurality of micro-LED array areas, to form apixel area and a pixel array area, and to remove the bank film in aboundary area between the second bank layers adjacent to each other;cutting the third substrate and the first substrate along a scribe zonethat is set in a boundary area between the second bank layers adjacentto each other; and separating a plurality of pixel arrays that includesthe plurality of thin-film transistor arrays and the plurality ofmicro-LED arrays from the first substrate and transferring the pluralityof pixel arrays onto a fourth substrate.
 16. The manufacturing method ofa micro-LED display device of claim 15, wherein a size and pattern ofthe plurality of thin-film transistor array areas is the same as a sizeand pattern of the plurality of micro-LED array areas.
 17. Themanufacturing method of a micro-LED display device of claim 15, whereinthe cutting the third substrate and the first substrate is performed bya laser.
 18. The manufacturing method of a micro-LED display device ofclaim 15, wherein the boundary area between the second bank layersadjacent to each other has a width greater than a width of the scribezone.
 19. The manufacturing method of a micro-LED display device ofclaim 15, wherein at least one of the plurality of pixel arrays has adifferent size.
 20. The manufacturing method of a micro-LED displaydevice of claim 15, further comprising forming a color filter layer ineach of the plurality of pixel arrays over the third substrate after thepatterning the bank film.